Refillable soft lead pencil

ABSTRACT

A pencil which has a tip and which dispenses a soft mass in use includes a sheath having front and back ends; a push rod positioned coxially within the sheath, having a sheath-side end, and being secured by its sheath-side end to the back end of the sheath in an axial direction; an elongate soft mass insert position coxially with the sheath; a front part which is a sleeve that envelopes the soft mass insert over at least a portion of its length, which is positioned coxially with the sheath and accommodated at least in part within the sheath, and which operates jointly with the sheath in the manner of a helical gear so that the fromt part retracts into the sheath by turning the front part relative to the sheath; and a soft mass insert holder which is connected to the front part so that it is engaged in the turning moment of the front part, which holds the elongate soft mass insert by one end thereof, which is rotatably secured to the push rod, and which is immovably secured to the push rod in the axial direction.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a pencil, in particular a pencil for dispensinga soft mass for cosmetic purposes.

2. Description of the Related Art

Such pencils comprise a sleeve-like sheath with a front end and a backend, a push rod that is arranged coaxially inside the sheath and issecured with one end in axial direction to the back end of the sheath,as well as a soft mass insert that is connected to the free end of thepush rod. The sheath and the front part are rotatably connected, in themanner of a helical gear. The front segment can be retractedtelescopically into the sheath through a relative turning of theaforementioned parts. The front part then releases the soft mass insert,secured relative to the sheath in axial direction. Such pencils fordispensing a soft mass are described, for example, in the referencesU.S. Pat. No. 5,364,197 and U.S. Pat. No. 5,366,311. In addition to theaxial movement, the front part of the known pencils for dispensing asoft mass also performs a turning movement, relative to the soft massinsert, during the extending or retracting movement. Owing to thefrequently sticky and soft consistency, the soft mass insert can stickto the inside of the front part, especially if it has not been used forsome time. If the front part is retracted in that case, it is possiblethat the soft mass insert will shear off as a result of the relativeturning movement between front part and soft mass insert.

SUMMARY OF THE INVENTION

Based on this, it is the object of the invention to improve a pencil ofthe aforementioned type with respect to this problem. This object issolved in that the soft mass insert is connected rotatably to the pushrod. If the soft mass insert sticks completely or only in some parts tothe inside surface of the front part, this does not have an adverseeffect, at least not during the retracting movement of the front part,since the soft mass insert can turn along with the front part as aresult of being rotatably secured to the push rod. A shearing off of thesoft mass insert is thus prevented. A design according to the inventionmakes sense even for pencils where the front part and the sheath areconnected such that they turn together and where the push rod, which isconfigured as a helical spindle and operates jointly with the frontpart, is located rotatably inside the sheath.

The soft mass insert of one preferred embodiment is held by the end of asoft mass insert holder, which points toward the pencil tip. The otherend of the soft mass insert holder is rotatably secured to the push rod,wherein the soft mass insert holder is connected such that it engages inthe turning moment of the front part. Such a design ensures that ashearing off of the soft mass insert is prevented, even with masses of avery soft consistency. The soft mass insert in this case does not turnalong because of a frictional or material engagement between soft massinsert and front part, but preferably because of a form-lockingengagement between front part and soft mass insert holder, which iseffective in turning direction. The rotatable connection between softmass insert holder and the tip-side end of the push rod is achieved witha very simple design, which is particularly easy to assemble in that acircular positioning groove exists on the inside surface of thesheath-side segment of the soft mass insert holder, into which anannular projection, arranged on the tip-side end of the push rod,engages in the manner of a snap connection.

In one preferred embodiment, the connection between sheath and frontpart in the manner of a helical gear is designed such that the push rodis rotatably secured to the sheath and has an external thread, intowhich the front part engages. It is particularly advantageous withrespect to the technical assembly if a snap connection with axiallyextending joining direction is effective between the external thread ofthe push rod and the front part. Such a snap connection isadvantageously realized in that a gripping jaw is formed onto thesheath-side end of the front part, which is engaged in the externalthread of the push rod and is elastically preformed in engagementdirection.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention is explained in further detail with theaid of-the attached drawings. Shown are in:

FIG. 1 A longitudinal section of a pencil according to the invention;

FIG. 2 The longitudinal section of a pencil according to FIG. 1, with asoft mass insert shortened through use and where the front part isretracted into the sheath;

FIG. 3 A cross section along the line III--III in FIG. 1;

FIG. 4 A cross section along the line IV--IV in FIG. 1;

FIG. 5 A cross section along the line V--V in FIG. 1 and

FIG. 6 The end of the front part of a pencil according to the invention,which operates jointly with the push rod.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As can be seen in FIG. 1 and in particular in FIG. 2, the maincomponents of a pencil according to the invention are a sleeve-typesheath 1, a sleeve-type front part 2, a push rod 3, a soft mass insertholder 4 and a soft mass insert 5. The push rod 3 is an essentiallycylindrical part with a helical groove 7 that extends screw-like aroundits longitudinal center axis 6 and forms an external thread. The backend of sheath 1 is closed off by a bottom 8, while its front end is opento receive the front part 2. When completely assembled, back end 12 ofpush rod 3, which faces the sheath bottom 8, has a segment with largerdiameter, namely, a head piece 9. A flange 13 is arranged at a distancein front of the back end 12 of push rod 3, which flange has two lock-inprojections 10, positioned diametrically opposite each other on itscircumferential surface. The lock-in projections 10 engage in lock-inrecesses 11 (FIG. 5) with a complimentary shape on the inside surface 14of sheath 1. As a result of this design, the push rod 3 is securedagainst rotation, relative to the sheath 1. A securing in the axialdirection is effected by an annular projection 15, arranged at adistance to the flange-type enlargement and near the end 12. On the sidefacing the flange 13, this annular projection is gripped from behind bya ring-shaped locking projection 16 that projects from the insidesurface 14 of sheath 1. The flange 13 rests against a stop collar 21that points toward the pencil tip 17 and projects radially inward fromthe inside surface 14.

There is no external thread on the end region of push rod 3, which facesthe pencil tip 17. This end region is divided into a first region 20,which follows the external thread or helical groove 7, and an adjoiningsecond region 23 that extends to the end 18 of the push rod. Thediameter of the first region 20 corresponds to the diameter of the pushrod region provided with an external thread. The second region has asmaller diameter and is used to fasten the soft mass insert holder 4.The soft mass insert holder 4 is essentially a sleeve, one end of whichis fitted during the assembly onto the second region 23 of push rod 3.Thus, when fully assembled, the region 23 is enveloped by the one end ofthe soft mass insert holder 4. In order to secure it in axial direction,a radially inward pointing annular projection 24 is arranged on theinside of the soft mass insert holder, which, when the device is fullyassembled, engages in a constriction 19 of the second region 23, in themanner of a snap connection. As a result of this design, the soft massinsert holder 4 is secured in the axial direction, but is rotatablyconnected with the push rod 3. With one of its ends, the soft massinsert 5 is inserted axially and secured against rotation in the regionof soft mass insert holder 4, which extends away from the annularprojection 24 and in the direction of pencil tip 17. The soft massinsert holder 4 essentially has the same diameter as the first region20. The push rod 3 and the soft mass insert holder 4 are arranged in thesheath center, wherein the soft mass insert holder 4 projects in partfrom the sheath or the sheath opening 25, arranged on the front endfacing away from the sheath bottom 8.

A hollow-cylinder shaped receiving space 22 for receiving the front part2 is arranged between the inside surface 14 of sheath 1 and the outsidecircumferential surface of the push rod 3 and soft mass insert holder 4.When assembled, the front part 2 is positioned at least partially in thereceiving space 22 and envelopes the push rod 3, the soft mass insertholder 4 and the soft mass insert 5, meaning it is arranged coaxially tothese parts.

FIG. 3 shows that the soft mass insert holder 4, as seen in the crosssection, has an octagonal contour. The inside surface 31 of the frontpart 2 has a complementary design, meaning the pencil insert holder 4 isembedded in the front part 2, such that it is form-locking in a turningdirection.

The end of front part 2, which is embedded in sheath 1 or which facesthe sheath bottom 8, has two windows 26 that are positioneddiametrically opposite each other. These windows are approximatelyU-shaped and circumscribe respectively one gripping jaw 27 extending inaxial direction, the free end of which points toward the sheath bottom8. The gripping jaws 27 have respectively one lock-in cam 28 on theinside facing the push rod 3, which cam engages in the helical groove 7.The front part 2 is connected in this way to the movement of push rod 3in the manner of a spindle drive. The gripping jaws 27 have a firstsegment 29 and a second segment 30. The second segment 30 adjoins thefirst segment 29 and extends to the free end of the gripping jaws 27.The upper surface 32 of segment 30 is beveled toward the free end of thegripping jaws 27. In the assembled state, only the region 33 of segment30, which adjoins the first segment 29, rests against the inside surface14 of sheath 1. The wall thickness of the first segment 29 is less thanthat of the second segment 30. The end region of the front part 2 withthe gripping jaws 27 turns via a slanted shoulder 34 into a region witha larger diameter, the outside circumferential surface of whichcooperates with the inside surface 14 of the sheath in the sense of asliding guide.

The operation of a pencil according to the invention is explained in thefollowing: Starting with the situation as shown in FIG. 1, a protectivecap 35, which may have been fitted onto the sheath 1, is initiallyremoved. The front part is in a maximum extended position. The lock-incams 28 in this case are arranged on the tip-side end of the helicalgroove 7. The soft mass insert 5, which has not yet been used, is longenough so that its end projects from the front part 2. Once theprojecting end is used up, the sheath 1 and the front part 2 are turnedrelative to each other, in that the sheath 1 is held in place, forexample, and the front part is turned in turning direction 39 (FIGS. 3,4). The soft mass insert 5 turns along in turning direction 39, sincethe soft mass insert holder 4 on the one hand is rotatably connected tothe push rod 3 and, on the other hand, is embraced in a form-locking wayby the front part, such that it effectively turns in direction 39. Ashearing off of the soft mass insert 5 as a result of a turning relativeto the front part is thus prevented. The lock-in cams 28 move along thehelical groove 7, so that the front part 2 is moved in a retractingdirection 40. Sheath 1 and front part 2 are turned in oppositedirections until the soft mass insert once more has a sufficientlyprojecting end. The front part 2 can be moved in the retractingdirection 40 until its end facing the sheath hits the head piece 9 ofpush rod 3, as shown in FIG. 2. In order to extend the front part, it isturned relative to the sheath and counter to the turning direction 40.

The assembly of a soft mass insert according to the invention takesplace as follows: First of all, the soft mass insert holder 4 with asoft mass insert 5 is fitted onto the push rod 3. The inserting movementin this case is in the direction of the longitudinal center axis 6 ofthe push rod or the soft mass insert holder and the soft mass insert. Atthe completion of fitting-on movement, the annular projection 24 on thesoft mass insert holder 4 snaps into the constriction 19 of the push rod3. Following this, the front part 2 is pushed from the pencil tip 17over the soft mass insert 5 and finally over the soft mass insert holder4, until the gripping jaws 27 with their lock-in cams 28 engage into thehelical groove 7. When fitting the front part 2 onto the soft massinsert holder 4, the gripping jaws 27 are deflected radially toward theoutside, in the direction of arrows 38. The segments 29 of the grippingjaws, which have reduced wall thickness, in this case act so-to-speak asfoil hinges. In a final step, the sheath 1 is fitted onto the end 12 ofpush rod 3. At the end of this inserting movement, the flange 13 hitsagainst the stop surface 21 on the inside surface 14 of sheath 1.

What is claimed is:
 1. A pencil which has a tip and which dispenses asoft mass in use, comprising:a sheath having fromt and back ends; a pushrod positioned coaxially within the sheath, having a sheath-side end,and being secured by its sheath-side end to the back end of the sheathin an axial direction; an elongate soft mass insert positioned coxiallywith the sheath; a front part which is a sleeve that envelopes the softmass insert over at least a portion of its length, which is positionedcoaxially with the sheath and accommodated at least in part the sheath,and which operates jointly with the sheath in the manner of a helicalgear so that the front part retracts into the sheath by turning thefront part relative to the sheath; and a soft mass insert holder whichis connected to the front part so that it is engaged in the turningmoment of the front part, which holds the elongate soft mass insert byone end thereof, which is rotatably secured to the push rod, and whichis immovably secured to the push rod in the axial direction.
 2. Thepencil according to claim 1 wherein the soft mass insert holder is asleeve, wherein the elongate soft mass insert is inserted with itssheath-side end in the segment of the soft mass insert holder whichfaces the pencil tip and which is enclosed by the front part in aform-locking way that is effective in a turning direction.
 3. The pencilaccording to claim 2, wherein a radially inward pointing annularprojection is arranged on the inside surface of the section of the softmass insert holder that faces the sheath, which projection engages inthe manner of a snap connection into a constriction, arranged on thetip-side end of the push rod.
 4. The pencil according to claim 3,wherein the push rod is attached to the sheath such that it rotates withthe sheath, and wherein the push rod has a helical groove in itscircumferential surface that forms an outside thread into which thefront part engages.
 5. The pencil according to claim 4, characterized bya snap connection that is effective between the helical groove and thefront part and for which the joining direction extends in axialdirection.
 6. The pencil according to claim 5, characterized by at leastone gripping jaw that is formed onto the sheath-side end of the frontpart, is engaged in the helical groove and is elastically prestressed inan engagement direction.
 7. The pencil according to claim 2, wherein thepush rod is attached to the sheath such that it rotates with the sheath,and wherein the push rod has a helical groove provided in itscircumferential surface that forms an outside thread into which thefront part engages.
 8. The pencil according to claim 7, characterized bya snap connection that is effective between the helical groove and thefront part and for which the joining direction extends in axialdirection.
 9. The pencil according to claim 8, characterized by at leastone gripping jaw that is formed onto the sheath-side end of the frontpart, is engaged in the helical groove and is elastically prestressed inengagement direction.
 10. The pencil according to one of the claim 1,wherein the push rod is attached to the sheath such that it rotates withthe sheath, and wherein the push rod has a helical groove provided inits circumferential surface that forms an outside thread into which thefront part engages.
 11. The pencil according to claim 10, characterizedby a snap connection that is effective between the helical groove andthe front part and for which the joining direction extends in the axialdirection.
 12. The pencil according to claim 11, characterized by atleast one gripping jaw that is formed onto the sheath-side end of thefront part, is engaged in the helical groove and is elasticallyprestressed in an engagement direction.
 13. The pencil according toclaim 1, wherein the push rod is attached to the sheath such that itrotates with the sheath and that it has a helical groove provided in itscircumferential surface that forms an outside thread into which thefront part engages.
 14. The pencil according to claim 13, characterizedby a snap connection that is effective between the helical groove andthe front part and for which the joining direction extends in axialdirection.
 15. The pencil according to claim 14, characterized by atleast one gripping jaw that is formed onto the sheath-side end of thefront part, is engaged in the helical groove and is elasticallyprestressed in engagement direction.